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  <a href="http://sudopedia.enjoysudoku.com/Uniqueness_Test.html#Uniqueness_Test_{7}.html">Uniqueness Test {7}</a>
   <p>
   The <b>{8} cells {3}</b> form a unique {0} with two common <b>candidates {1} and {2}</b>.
   There are two possibilities to place the two digits into the {8} cells which leads to an invalid puzzle with two solutions.
   This <a href="http://sudopedia.enjoysudoku.com/Deadly_Pattern.html">deadly pattern</a> must be avoided because a valid puzzle can have just one solution.
   To avoid the deadly pattern extra candidates in one or several of the {8} cells exist to eliminate other candidates in the puzzle. 
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   <p>
   The highlighted <b>cells {5}</b> are the only cells with an extra <b>candidate {6}</b>.
   To avoid the deadly pattern one of the {9} cells must contain <b>digit {6}</b>.
   Therefore <b>digit {6}</b> can be eliminated from any cell seen by the <b>{9} cells {5}</b>.
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